Trammel point



' i S. GRACE.

TRAMMEL POINT.

APPLICATION FILED NOV-11,

Patqnted Aug. 29, 1922.

WEL me HENRY s. GRACE, or'sAN FRANCISCO, CALIFORNIA, ASSIG-NOR o a. :r'. MCDON LD, on v saw. nnAnorso o LrronNr j,

TRA MEL roman To all whom it may concern." Be it known that I, HENRY GRACE, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State o-fCalifornia, have invented new and useful Improvements in-Trammel Points, of which the following is a. specifi cation.

This invention relates to improvements in trammel point-s or beam compasses. The object of the invention is to provide a beam compass which will be easier to operate than those heretofore used and which will he graduated either to sixtysfourths of'an inch or on the metric system to one-thousandths of an inch.

In the accompanying drawing, Figure 1 is a broken front elevation-of my improved beam compass; Figure 2 is a similar view of the operative end thereof on an enlarged scale; Figure 3 is a plan view of a portion thereof; Figure 4- is aside view of. the portion shown in Figure 3 looking from the side opposite from Figure 2.

Referring to the drawings, 1 indicates the beam of my improved beam compass, a portion only being here shown. Near one end of said beam is clamped thereto a U-shapedholder 2. Through holes 3 in one side thereof slide guide pins 4, the inner ends of which are attached to a spring clamp sheet 6 which is clamped against the beam 1 between the flanges 7 and 8 thereof by a screw 9 screwed through the side of the U-shaped holder through which the pins 4: extend and the inner end of which bears against the clamp sheet 6. By turning said screw by means of the handle 10, the clamp sheet 6 may be clamped firmly against a side of the beam between the flanges 7 and 8 and thus firmly secure the U-shaped holder in position Upon the outer side of the middle portion of said holdereis pivoted, as shown at 11,

a compass leg 12 having adjustably secured therein a needle 13, andfor the purpose of I turning said leg upon its pivot 11, said leg is provided with an arm 14 extending at right angles thereto and forked at its free outer end, as shown at 15 to extend on opposite sides of a screw 16 fixedly attached to the middle side of the U-shaped clamp holder, a nut 17 being provided to turn upon said screw, and outside of said arm, and thus move said arm inwardly. The free end of a spring 18 bears against the inner side of .marking member 28 spe of a em y; f Patented Aug. 29, 1922.. Application filed November 17,1920. seriarivo. 424,651. i

said arm and movesit outwardly, said arm being secured at said end'as show-n at 19 to the U-shaped 1 holder By turning said nut, the position of the leg may be varied as desired, although in: general no change will be made in the position ofthis point, as the difference in the. positions of the compass will be made in .the other. member thereof, which I am about to describe. 22 indicates a U-shaped holder, similar in stituted by the stem of a pencil carrying member. I

Said square bar 25 is extended in the opposite direction to the ink carrying member in the form of a long screw 29 which extends through a bearing 30 supported by a support 31 extending from the other end of said U-shaped holder 22, a coiled spring 32 surrounding said screw and bearing at its general construotion to the ,Ushaped holder 2, from one rear end against said bearing 30 and at its v front end against a washer 34L surrounding said screw and abutting against therear end of the square portion of said bar 25. Said helical spring thus constantly presses the 1 squarebarand'the inking member carried thereby towards the leg 12. A cylinder 33 is graduated as shown at 35, and a mark 36 is carried on the bearing 30 to which mark one of said graduations 35 isbrought into alinement. threaded extension 29 of the bar 25 for convenience in manipulation. It is obvious that by turning said wheel through the space between two adjacent graduations 35, the

will be advanced towards the stationary member 12' by means of the spring18, Said square hollow bar is graduated on one side every one-thirty-sec- A .wheel 37 surrounds the" 0nd of an inch and on the opposite side every one-sixteenth of an inch, and on the outer side every onesixty-fourth of an inch, so that by observing how far said bar projects beyond said bearing, the distance of the marking point from the stationary point can be estimated in sixty-fourths of an inch, thirty-seconds of an inch, one-sixteenths of an inch, as may be desired.

If one revolution of the cylinder 33 corresponds to an advance of the bar 25 through a distance equal to one thread of the screw and there are twenty five graduations in the cylinder and if there are forty threads of the screw to the inch, then each of the graduations of the cylinder would correspond to one-one-thousandths of an inch.

I claim:

1. In a beam compass, the combination of a beam, a stationary point carried thereby, a movable point, and means for regulating the distance of the second point from the first point,'which means comprises a holder slidable upon the beam, bearings carried by the holder, a bar movable longitudinally in the bearings and having one end portion thereof formed angular in cross section, one of said bearings being of angular form to receive the angular portion so as to prevent turning of said bar, said bar being provided with screw threads at its other end portion, an adjusting nut turned on the screw threaded portion of the bar, means for preventing longitudinal movement of the nut, said bar where angular being graduated on one face, every one-thirty-second of an inch, on another face every one-sixteenth of an inch, and on another face, one-siXtyfourth of an inch, said screw threaded portion having forty screw threads to the inch and a cylindrical portion on the nut on which there are twenty-five graduations.

2. In a beam compass, the combination of a beam, a stationary point, a movable point, means for regulating the distance of the second point from the first point by either ordinary fractions of an inch or by thousandths of an inch, as desired, which means comprises a holder slidable upon the beam, bearings carried by the holder, a bar movable longitudinally in the bearings and having one end portion thereof formed angular in cross section, one of said bearings being of angular form to receive the angular portion so as to prevent turning of said bar, said bar being provided. with screw threads at its other end portion, an adjusting nut turned on the screw threaded portion of the bar, means for preventing longitudinal movement of the nut, said bar where angular, being graduated on one face, every onethirty-second of an inch, on another face every one-sixteenth of an inch, and on another face, one-siXty-iourth of an inch, said screw threaded portion having forty screw threads to the inch, a cylindrical portion on the nut on which there are twenty-five graduations and a spring against the action of which said bar is moved.

' HENRY S. GRACE. 

